Quick setting materials are required for emergency repair of roads, slip-prevention for water stopping walls, water stopping works, repairing works for roads, building materials or structural materials, as well as in secondary product plants requiring improved rotation rate for forms.
As properties required for quick setting materials used in various fields as described above, it is of course essential that they set at an early stage after kneading, as well as they easily penetrate into cracks to be repaired or gaps in strata and can be cast easily into forms. That is, it is required for kneading products that they maintain such a predetermined fluidity as being capable of satisfactory processability till the completion of casting work. Further, since such materials are building materials and, generally, used in a great amount, it is also an important condition that the starting material is inexpensive.
Heretofore, there have been used for such quick setting materials, portland cement or mixed i.e. blended cement and a coagulation promoter added thereto such as sodium carbonate, calcium chloride or water glass, or quick setting cement such as alumina cement or jet cement.
However, among the conventional materials as described above, the quick setting material comprising portland cement or mixed cement and the coagulation promoter added thereto are poor in the developability of early strength after kneading and can not be applied to such places as requiring high strength. Further there are additives containing water soluble materials, which leach out during working or after setting, to possibly cause public pollution.
On the other hand, since quick setting cements such as alumina cement or jet cement require temperature, for example as high as 1330.degree. to 1450.degree. C. and a long time for sintering, they are extremely expensive. Therefore, since the quick setting cements are highly expensive, their use is restricted only to special works or to a case of requiring emergency and there is a limit for the range of application use. In particular, the jet cement involves a problem that the fluidity is lost just after kneading and the time keeping the fluidity required for the workings after kneading is not long. For overcoming such a drawback, if a coagulation retarder is used for prolonging the usable time, no sufficient effect for the improvement can be obtained thereby fail to attain satisfactory workability.
The present inventors have made earnest studies for dissolving the foregoing problems in the prior art and, as result, have found that a metallurgical slag comprising, as a main ingredient, calcium aluminate yielded in a great amount as by-product in a case of using aluminum for the acid removing step in steel making and refining processes has an effective property as the starting material for the quick setting composition and have previously filed a quick setting composition comprising the metallurgical slag as the ingredient prior to the present applicant (Japanese Patent Laid-Open Sho 62-260749 and Japanese Patent Laid-Open Application Sho 63-277542).
In these quick setting compositions, quick setting property is obtained by using a quick setting ingredient prepared by mixing and pulverizing a metallurgical slag containing 12 CaO.7 Al.sub.2 O.sub.3 as the main ingredient and II-type anhydrous gypsum and a coagulation controlling agent (retardation controller) together with ordinary Portland cement or mixed cement.
Since these quick setting compositions have excellent properties such that they are satisfactory in view of the fluidity within a predetermined period of time after kneading and remarkably excellent in the developability of strength after the usable time, they are used in various applications.
However, such quick setting compositions still have the following problems (1)-(3) to be dissolved.
(1) In a case where the amount of the quick setting ingredient (metallurgical slag, II-type anhydrous gypsum and coagulation controlling agent) to be added to the cement is small (for example, less than 20%) and if the working temperature is lower than 10.degree. C., the strength developability is extremely poor.
(2) The addition amount of the coagulation controlling agent for obtaining an identical usable time differs greatly depending on the working temperature make it difficult to control the addition amount.
(3) Since the metallurgical slag is a by-product resulting from steel making and refining processes, chemical ingredients fluctuate and the strength developability of the quick composition or the like varies depending on the chemical ingredients to sometimes fail to obtain sufficient property.
For instance, a quick setting composition using a metallurgical slag with the CaO/Al.sub.2 O.sub.3 ratio of not greater than 1.3 shows satisfactory developability for strength in a short time of three hours of material age but increase of the strength after one day of material age, three day of material age and 7 day of material age is extremely poor.